Bone biopsy needle

Abstract

A bone biopsy instrument kit includes a hollow needle with an annular cutting edge which is rotated to cut a core of bone sample which is retained in the internal passage of the needle. A semi-circular portion of the needle wall is removable to withdraw the core sample without compressing or otherwise changing the consistency of the sample. The annular cutting edge has a sawtooth configuration with a side rake angle causing bone dust to be expelled radially without contaminating the core sample. An elongated obturator and an elongated trocar may be inserted through the needle to direct the annular cutting edge through tissue and to center and guide the instrument into the surface of the bone.

I claim: 
     
       1. A bone biopsy instrument kit comprising: (a) an elongated hollow cylindrical needle having a passage therethrough and an annular cutting edge at one end thereof, said needle comprising a first elongated section, at least a portion of its length having a semi-cylindrical configuration as viewed in cross-section, and a second elongated section having a semi-cylindrical configuration as viewed in cross-section, each said section having a pair of surfaces which abut the respective surfaces of the other section to form said hollow needle;   (b) means for releasably securing said semi-cylindrical sections together with said pairs of surfaces in abutting relationship;   (c) a handle having means releasably engaging the end of said needle opposite said one end, said handle having a straight passage therethrough in alignment with said passage in said needle;   (d) an elongated trocar having a point at one end and extending through said passages in said handle and needle and positioned with said point projecting beyond said annular cutting edge; and   (e) means for releasably securing said trocar in said position in said needle;   (f) whereby said hollow needle with said point of said trocar extending beyond said annular cutting edge may be rotated to cut into the surface of a bone, said trocar withdrawn through said handle, said annular cutting edge of said needle driven a predetermined distance through said bone with a sample of said bone retained in said passage in said needle, said needle withdrawn from said bone with said sample retained in said passage, and said first and second sections of said needle separated to remove said sample.   
     
     
       2. A bone biopsy instrument kit according to claim 1 wherein said annular cutting edge at said one end of said needle has a sawtooth configuration. 
     
     
       3. A bone biopsy instrument kit according to claim 2 wherein said elongated hollow cylindrical needle further comprises an annular cutting ring having said sawtooth configuration, said annular cutting ring being secured to said first elongated section at said one end of said needle. 
     
     
       4. A bone biopsy instrument kit according to claim 3 wherein said sawtooth configuration of said cutting ring comprises a plurality of sawteeth arranged sequentially about said cutting edge, said teeth being at a side rake angle with respect to a line passing through the axis of said cutting ring such that bone dust generated during cutting is displaced radially outwardly as said needle is rotated in one direction. 
     
     
       5. A bone biopsy instrument kit according to claim 4 wherein said side rake angle is about 15°. 
     
     
       6. A bone biopsy instrument kit according to claim 1 wherein at least one of said pair surfaces on one of said sections has at least one projection and at least one of said pair of surfaces on the other of said semi-cylindrical sections has at least one corresponding recess which at least one projection and at least one recess register when said sections are assembled to form said needle to maintain alignment of said semi-cylindrical sections. 
     
     
       7. A bone biopsy instrument kit according to claim 1 wherein said means for releasably securing said sections together comprises at least one annular member surrounding a portion of the length of said needle. 
     
     
       8. A bone biopsy instrument kit according to claim 7 wherein said at least one annular member is slidable along a substantial length of said needle and includes means for securing said annular member at any predetermined position along said length whereby said at least one annular member serves as an indicator of the depth of said cutting edge in said bone. 
     
     
       9. A bone biopsy instrument kit according to claim 7 wherein said at least one annular member comprises a first annular member surrounding a portion of the length of said needle and means for pressing at least a portion of said first annular member tightly against the surface of said needle to prevent said first annular member from moving axially along the length of said needle. 
     
     
       10. A bone biopsy instrument kit according to claim 9 wherein said means for pressing said first annular member against the surface of said needle comprises second and third annular members having corresponding male and female-threaded members respectively surrounding said needle and said first annular member, the interior surfaces of said second and third annular members being conical shaped such that when said second and third annular members are screwed towards each other said first annular member is cammed into tight engagement with the surface of said needle. 
     
     
       11. A bone biopsy instrument kit according to claim 1 wherein at least one of said sections of said needle comprises an enlarged portion spaced from said annular cutting edge for reinforcing said needle and increasing stability of said cutting edge. 
     
     
       12. A bone biopsy kit instrument according to claim 1 wherein the geometrical configuration of the portion of said hollow needle adjacent said opposite end is non-cylindrical and said means at one end of said handle for releasably engaging said opposite end of said needle comprises a recess having a corresponding geometrical configuration therein whereby said hollow needle may be rotated during cutting of said bone by rotating said handle. 
     
     
       13. A bone biopsy instrument kit according to claim 12 wherein said handle further comprises ratchet means permitting said needle to be rotated by rotation of said handle in only one direction, said needle being stationary during rotation of said handle in the opposite direction. 
     
     
       14. A bone biopsy instrument kit according to claim 1 further comprising an aperture passing through each of said sections of said needle and said trocar when said trocar is in said normal position with said point projecting beyond said annular cutting edge, and removable pin means positioned in said aperture to retain said trocar in position in said needle, whereby said trocar may be withdrawn from said passage in said needle after withdrawing said pin from said aperture. 
     
     
       15. A bone biopsy instrument kit according to claim 1 further comprising an elongated obturator rounded at one end and adapted to extend through said passages in said handle and needle, in place of said trocar, said releasable securing means securing said obturator in place with said rounded end projecting beyond said annular cutting edge to serve as a guide as said bone biopsy instrument is pressed through the soft tissue and muscle towards the surface of the bone of a patient.